This paper reconstructs the 1928–1929 correspondence between Reichenbach and Einstein about the latter's latest distant parallelism-unified field theory, which attracted considerable public attention at the end of the 1920s. Reichenbach, who had recently become a Professor in Berlin, had the opportunity to discuss the theory with Einstein and therefore sent him a manuscript with some comments for feedback. However, the subsequent correspondence took an unpleasant turn. While their letters point to a deterioration of their personal relationships, their published writings reveal a deeper intellectual estrangement. In his efforts to unify electricity and gravitation, Einstein had abandoned the physical heuristic that guided him to the relativity theory, to embrace a more speculative, mathematical heuristic, which he and Reichenbach had both condemned in the past. Amidst the tragedy of the 1930s, a decade-long personal and intellectual friendship grew fainter and never recovered. This paper, relying on archival material, aims to revisit the Reichenbach-Einstein relationship in the late 1920s in light of Reichenbach’s neglected contributions to the epistemology of the unified field theory program. Reichenbach was among the first to realize that Einstein conceived the latter as a unification, rather than as a geometrization program. Thereby, Reichenbach outlined one of the first philosophical reflections on the relationships between geometrization and unification in physics.